EXTERNAL ANATOMY. FEATHERS. 77 
also remarkably conspicuous upon the breast of the herons, 
where it exists unmixed with any other feathers, and 
contains, moreover, a white powdery substance, the use 
of which is unknown. It is curious that the breast of 
the herons should have a protection of this kind, when the 
back of their neck, which is equally destitute of true 
feathers, has none. But it is obvious, from the wading 
hahits of these birds, that their breasts are much more 
likely to come into contact with the water than the hack 
of their necks, seeing that the latter part is only thrown 
out and extended for a moment when tlie bird suddenly 
seizes its prey, whereas tlie breast, if the bird is wading, 
may be exposed for some time to the action of the water. 
Birds, whose bodies are supplied with a great quantity 
of down, instinctively employ it to Une their nests, as 
the eider is well known to do. 
(71.) The regular external feathers of the body, 
like those of the witigs and tail, are very differently con- 
structed from such as are called the down ; they are 
externally composed of three parts or substances : 1. 'I’he 
down ; 2. The laminie, or webs ; and, 3. The shaft, or 
quin, on the sides of which the two former are arranged. 
The downy laminte, or webs of these feathers, are very 
different from the substance we have just described, since 
they not only have a ilistinct shaft of their own, but the 
laminsB which spring from both sides of it are percep- 
tibly and regularly arranged, although, from being devoid 
of all elasticity, hke true down, they do not unite and re- 
pose parallel to each other. The soft downy lamiiiis are 
always situated close to the insertion of the quill into the 
skin ; and although, for obvious reasons, they are more 
developed on those feathers which cover the body, they 
likewise exist on .such as are employed in flight, as 
shown in the quill of a goose ; and as they are always 
concealed from sight when the plumage is uninjured, 
and are not exposed to the action of tlie air, so they are 
always colourless. The third part of a feather consists in 
the true external laminte, which are arranged in two 
series, one on each side the shaft; and these sides 
